variable stage and single stage air conditioners

Single Stage or Variable Speed A/C Units?

Single Stage or Variable Speed A/C Units?

Single, Dual, or Variable Speed A/C Systems?

If you have been told you need a new air conditioning system and you are researching the various types of A/Cs, it is probable you’ve heard the terms single stage, two-stage or dual stage, and variable speed or variable stage. What’s the difference in these types of systems?
Let’s look at these three types of A/C units and how they function, their benefits, and the costs.


The A/C compressor is the pump that moves the refrigerant between the evaporator coils that removes heat and humidity from the air to the condenser that uses the refrigerant to chill the indoor air. The compressor gets a signal from the thermostat indicating what the homes desired temperature should be and runs the system accordingly.

How the Compressors Work
• A single-stage compressor operates at one speed. It’s either 100% on, or 100% off – there is no in between.
• A Dual or Two-stage compressor operates at two-speeds, low and high.
• A variable speed compressor operates at speeds between 25% and 100%. This allows the AC to cool your home at lower speeds for longer periods of time, while still maintaining higher speeds when the outdoor temperature gets hot. (Understanding the technology details)

Variable Speed Benefits

The variable speed air conditioner beats out the single-stage air conditioners when it comes energy efficiency and the home’s comfort.
• A single-stage air conditioner has shorter, more frequent on and off cycles. A single stage system can start and stop up to 72 times in a 24-hour period during peak season. That causes a lot of wear and tear on the system.
• A variable speed air conditioner runs continuously at a lower setting, which uses less energy, for longer periods of time. The most energy consumed in a cycle is when the system is turning on. Because variable speed systems have fewer on and off cycles, so it costs less to operate.

System Run Time

Continuous and longer run times in the Variable Speed compressors increases your home comfort in two ways:
1. Reduced humidity – Longer running times means your system has more time to remove the humidity from the air.
2. Even temperatures throughout your entire home – As the fan blows for longer periods of time, your home benefits from better air circulation and fewer hot/cold spots.
3. Cleaner air – variable speed systems that include products like the Air Scrubber Plus® or UV germ eliminating lights are constantly recirculating and cleaning the air of microbial particles, bacteria and pollutants.

Variable vs. Single Stage Costs

It’s a natural assumption that the single stage is the less expensive than the variable speed. While the variable speed does cost more upfront in the long-term your investment will pay off in the comfort benefits, energy savings and lower utility bills. gained. A single-stage system is a good system, but the variable speed system is the best option if you are going to be in your home long-term or for resale value.
If you’re on a tight budget and need the most affordable upfront cost, then a single-stage can get the job done. If you want the lowest energy cost and reduced humidity, and most consistent comfort, then a variable speed system is our recommendation. Maybe you’re looking for something in the middle, like the two-stage system – this system offers some of the benefits of a variable speed at a lower cost.

There are several other factors that can influence your decision on the type of system that is best for your comfort needs and your home and all need to be measured before making the final decision. The comfort advisors at TemperaturePro San Antonio can help you review all the factors and assist with any questions you may have. Schedule an in-home consultation today. 210-858-5566


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